Flash thermography device having moveable arm for inspecting internal turbine components

ABSTRACT

A flash thermography device for generating an infrared image of a turbine component located inside a turbine. The device includes a flash enclosure having an aperture. A flash source is located in the aperture wherein the flash source generates a light pulse that heats the turbine component. The device also includes an infrared sensor for detecting thermal energy radiated by the turbine component wherein the radiated thermal energy is transmitted through the aperture to the infrared sensor to enable generation of an infrared image of the turbine component. Further, the device includes moveable arm that holds the flash enclosure and infrared sensor wherein the arm is inserted through an opening in the turbine to enable positioning of the flash source and infrared sensor in close proximity to the turbine component.

FIELD OF THE INVENTION

This invention relates to flash thermography devices used in connectionwith turbines, and more particularly, to a flash thermography devicehaving a flash enclosure that includes a flash source for heating aturbine component and an infrared sensor for detecting thermal energyradiated by the turbine component wherein the flash enclosure andinfrared sensor are located on a moveable arm and wherein the flashsource and infrared sensor are inserted through an opening in theturbine to enable positioning in relative close proximity to a turbinecomponent inside the turbine to enable generation of an infrared image.

BACKGROUND OF THE INVENTION

In various multistage turbomachines used for energy conversion, such asgas turbines, a fluid is used to produce rotational motion. Referring toFIGS. 1 and 2, side and perspective partial cross sectional views of anaxial flow gas turbine 10 is shown. The turbine 10 includes a compressorsection 12, a combustion section 14 and a turbine section 16 arrangedalong a horizontal center axis 18. The combustion section 14 includes aplurality of combustors 28 arrayed about the combustion section 14 thatare in fluid communication with a combustion section 14 interior. Eachcombustor 28 includes a top hat portion 30 and a removable supporthousing 32. The compressor section 12 provides a compressed air flow tothe combustion section 14 where the air is mixed with a fuel, such asnatural gas, and ignited to create a hot working gas. The turbinesection 16 includes a plurality of turbine blades 20 arranged in aplurality of rows. The hot gas expands through the turbine section 16where it is directed across the rows of blades 20 by associatedstationary vanes 22. The blades 20 are each configured as a bladeassembly that is attached to a shaft that is rotatable about the centeraxis 18. As the hot gas passes through the turbine section 16, the gascauses the blades 20 and thus the shaft to rotate, thereby providingmechanical work. Each row of blades 20 and associated vanes 22 (i.e.collectively, “airfoils”) form a stage. In particular, the turbinesection 16 may include four rows of blades 20 and associated rows ofvanes 22 to form four stages. The gas turbine 10 further includes anexhaust cylinder section 24 located adjacent the turbine section 16 andan outer diffuser section 26 located adjacent the exhaust cylindersection 24.

Sections of the turbine 10 that are exposed to the hot gases as thegases travel along a hot gas path in the turbine 10 may include aceramic-based coating that serves to minimize exposure of the base metalof a component, such as an airfoil base metal, to high temperatures thatmay lead to oxidation of the base metal. Such a coating may be a knownthermal barrier coating (TBC) that is applied onto a bond coating (BC)formed on the base metal.

A turbine 10 is typically operated for extended periods. The TBC layeror both the TBC and BC layers may undesirably deteriorate or delaminateduring operation of the turbine 10. This exposes the base metal to hightemperatures, which may lead to oxidation of the base metal. A turbineis inspected at periodic intervals to check for wear, damage and otherundesirable conditions that may have occurred with respect to variousinternal components. In addition, the TBC/BC layers are inspected todetermine the degree of deterioration of the TBC/BC layers (i.e.remaining thickness of the layers) and other undesirable conditions. Inorder to inspect components within the turbine 10, the turbine 10 isshut down and allowed to cool down, which takes a substantial amount oftime. An inspection/evaluation team must then disassemble substantialportions of the turbine 10, such as an outer casing 34 and associatedcomponents, in order to gain access to a desired internal turbinecomponent and perform an assessment or inspection of the turbinecomponent. However, the current procedure for inspection is laborintensive, time consuming and expensive.

SUMMARY OF INVENTION

A flash thermography device for generating an infrared image of aturbine component located inside a turbine is disclosed. The deviceincludes a flash enclosure having an aperture. A flash source is locatedin the aperture wherein the flash source generates a light pulse thatheats the turbine component. The device also includes an infrared sensorfor detecting thermal energy radiated by the turbine component whereinthe radiated thermal energy is transmitted through the aperture to theinfrared sensor to enable generation of an infrared image of the turbinecomponent. Further, the device includes a moveable arm that holds theflash enclosure and infrared sensor wherein the arm is inserted throughan opening in the turbine to enable positioning of the flash source andinfrared sensor in close proximity to the turbine component.

Those skilled in the art may apply the respective features of thepresent invention jointly or severally in any combination orsub-combination.

BRIEF DESCRIPTION OF DRAWINGS

The teachings of the present disclosure can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 is a side partial cross sectional view of an axial flow gasturbine.

FIG. 2 is a perspective partial cross sectional view of an axial flowgas turbine.

FIG. 3 depicts a flash thermography device for imaging a turbinecomponent in accordance with an embodiment of the invention.

FIG. 4A shows the flash thermography device mounted to a moveable arm.

FIG. 4B is an enlarged view of balloon section 4B of FIG. 4A.

FIG. 5 is a partial cross sectional view of the turbine wherein theflash thermography device is shown inserted through an opening of theturbine in order to capture an IR image of a turbine component.

FIG. 6 is a high-level block diagram of a computer.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

Although various embodiments that incorporate the teachings of thepresent disclosure have been shown and described in detail herein, thoseskilled in the art can readily devise many other varied embodiments thatstill incorporate these teachings. The scope of the disclosure is notlimited in its application to the exemplary embodiment details ofconstruction and the arrangement of components set forth in thedescription or illustrated in the drawings. The disclosure encompassesother embodiments and of being practiced or of being carried out invarious ways. Also, it is to be understood that the phraseology andterminology used herein is for the purpose of description and should notbe regarded as limiting. The use of “including,” “comprising,” or“having” and variations thereof herein is meant to encompass the itemslisted thereafter and equivalents thereof as well as additional items.Unless specified or limited otherwise, the terms “mounted,” “connected,”“supported,” and “coupled” and variations thereof are used broadly andencompass direct and indirect mountings, connections, supports, andcouplings. Further, “connected” and “coupled” are not restricted tophysical or mechanical connections or couplings.

Referring to FIG. 3, a flash thermography device 40 for imaging aturbine component in accordance with an embodiment of the invention isshown. The device 40 includes an infrared (IR) sensor portion 42 fordetecting thermal energy in the infrared region of the electromagneticspectrum. In an embodiment, the IR sensor 42 is an IR camera having alens 44 although it is understood that other types of IR sensors may beused. By way of example, the IR sensor 42 may be an IR camera such asthat available from FLIR Systems, Boston, Mass., US. In an embodiment, amicrobolometer is used as a detector in the IR camera to reduce the needfor cooling of the sensor. The device 40 is configured to capture IRimages of internal portions of a turbine 10.

The device 40 also includes a flash enclosure 46 having an enclosureaperture 48 that exposes the lens 44 to enable detection of thermalenergy by the IR sensor 42. A flash source 50 is located around aperiphery of the enclosure aperture 48. In an embodiment, the flashsource 50 has an annular shape that includes a flash aperture 52 that isaligned with the enclosure aperture 48 and the lens 44. The flash source50 may be configured as a flash tube although it is understood thatother types of flash sources may be used. The flash enclosure 46 mayalso include a substantially cone shaped reflector 51. The device 40further includes a flash power supply 54 connected between a computer 56and the flash source 50 by electrical connections 58. The flash source50 is energized by the flash power supply 54 thereby causing the flashsource 50 to emit a light pulse that heats a component, such as aturbine component. A portion of the thermal energy radiated by thecomponent travels through the enclosure 48 and flash 52 apertures and isdetected by the IR sensor 42. The IR sensor 42 generates IR images ofthe component based on the thermal energy radiated by the component. TheIR sensor 42 may also be configured to obtain image data at otherfrequencies in addition to or in place of the infrared region of theelectromagnetic spectrum.

Referring to FIGS. 4A-4B, the device 40 is mounted to an end of anextendable or telescopic arm 70 by an attachment bracket 72. In use, anoperator is able to insert the device 40 and arm 70 through an openingin the turbine 10 and move the arm by extending, retracting and/ororienting the arm 70 as desired. This enables positioning of the device40 in relative close proximity to an item of interest within the turbine10, such as the row 1 vanes, and capturing of a close up IR image of theitem of interest. An optical camera 74 and associated lamp 76 are alsomounted to the enclosure 46. The optical camera 74 is coupled to adisplay 75 that enables an operator to observe components, systems andsurfaces located within the turbine 10 that are within a field of viewof the optical camera 74. The lamp 76 illuminates internal portions ofthe turbine 10 to assist in viewing the interior of the turbine 10 andnavigating the device 40 to a desired position within the turbine 10 tocapture an image with the device 40. In an embodiment, the attachmentbracket 72 may include at least one hinge 79 to enable a vertical and/orhorizontal sweeping motion of the device 40 to provide additionalviewing angles. With respect to optical inspection systems, thedisclosure of U.S. Patent Publication No. 2013/0194413 A1, applicationSer. No. 13/362,417, published on Aug. 1, 2013, entitled SYSTEM ANDMETHOD FOR AUTOMATED OPTICAL INSPECTION OF INDUSTRIAL GAS TURBINES ANDOTHER POWER GENERATION MACHINERY to Hatcher et al. is herebyincorporated by reference in its entirety. In addition, the disclosureof application Ser. No. 14/684,471, filed on Apr. 13, 2015, entitledSYSTEM TO PROGNOSE GAS TURBINE REMAINING USEFUL LIFE to Iyer et al. isalso hereby incorporated by reference in its entirety.

The device 40 and arm 70 are sized to enable insertion of the device 40and arm 70 through an opening in the turbine 10. In an embodiment, thedevice 40 and arm 70 may be inserted through an approximately 4.5 inchsize opening available in a large turbine. For example, the device 40and arm 70 may be inserted through an opening 53 in the pilot cone 60 ofthe combustor basket portion 62 as shown in FIG. 5. As previouslydescribed, the combustion section 14 includes a plurality of combustors28 arrayed about the combustion section 14 that are in fluidcommunication with a combustion section 14 interior. Each combustor 28includes a top hat portion 30 and a removable support housing 32.Referring to FIG. 5, a selected support housing 32 is shown removed.FIG. 5 is a partial cross sectional view of the turbine 10 wherein thedevice 40 and arm 70 are shown inserted through the opening 53 in thepilot cone 60 in order to capture an IR image of a turbine component.Removal of the support housing 32 provides access to the opening 53 inthe pilot cone 60. In accordance with the invention, the device 40 andarm 70 are sized to enable insertion of the device 40 and arm 70 throughthe opening 53. The arm 70 may then be extended, retracted and/ororiented at an angle α as desired to enable positioning of the device 40in relative close proximity to an item of interest in the turbine 10,such as the row 1 vanes 66, and capturing of an IR image of the row 1vanes 66. Thus, IR images of the interior of the turbine may be obtainedthat are outside of a line of sight view typically available through aturbine inspection port, for example. The arm 70 may be hand held andmoved by an operator. Alternatively, the arm 70 may be affixed to amounting fixture using preexisting apertures 68 used for securing asupport housing 32. It is understood that other openings in the turbine10 may be used to capture IR images of internal portions of the turbine10.

In order to obtain an IR image of a component such as vane 66, the flashsource 50 is energized by the flash power supply 54 thereby causing theflash source 50 to emit a light pulse that heats the vane 66. Forexample, the flash source 50 provides approximately 5000 to 6000 Joulesof energy output to heat at least one vane 66. The duration of lightpulse may depend on the thickness of a BC or TBC layer being inspectedon vane 66. A portion of the thermal energy radiated by the vane 66 isthen detected by the IR sensor 42. The IR sensor 42 generates IR imagesof the vane 66 based on the thermal energy radiated by the vane 66. Thelength of time used for detecting the radiated thermal energy (i.e.signal collection time) is dependent upon the characteristics of thecomponent that is being imaged. Thus, in the current embodiment of theinvention, IR images of internal turbine components, such as row 1 vanes66, are obtained non-intrusively and without removal of the main casing34 of the turbine 10. In accordance with aspects of the invention, othercomponents along a turbine a hot gas path may also be imaged such astransition components, blades and others. Thus, the present inventionenables inspection of turbine components while requiring minimaldisassembly of the turbine, resulting in substantial time and costsavings. When the IR sensor 42 being used is a midrange IR camera (i.e.having a spectral range of approximately 3.0-5.0 μm), an opaque materialor other material (i.e. graphite) may be used on the TBC layer in orderto increase an emissivity of thermal energy emitted by a turbinecomponent being imaged and increase sensitivity of the data.Alternatively, an opaque layer on the TBC layer is not needed if a longwave IR camera (i.e. having a spectral range of approximately 7.5-9.5μm) is used since it has been found by the inventors herein that the TBClayer itself serves as an opaque layer when using a long wavelength.Examples of a midrange IR camera and a long wave IR camera include FLIRSystems models SC4000 and A35, respectively.

It has been found by the inventors herein that IR images of a componentobtained by the device 40 provide sufficient detail of the component toenable evaluation by an inspection/evaluation team. Further, the device40 generates IR images having sufficient detail to enable determinationof a thickness of a BC or TBC layer formed on a component using knownmethods. Therefore, the current invention enables nondestructiveevaluation (NDE) of turbine components. If there is significant damageto the BC/TBC layers, the inspection/evaluation team can quickly make adecision to call for maintenance in order to avoid damage of a turbinecomponent due to loss of BC/TBC layers.

Referring back to FIG. 3, the IR sensor 42 is communicatively coupled tothe computer 56 by electrical connection 58 or a wireless connection.The computer 56 includes software and drivers for controlling operationof the IR sensor 42, flash power supply 54 and flash source 50. Thecomputer 56 may use well-known computer processors, memory units,storage devices, computer software, and other components. A high-levelblock diagram of such a computer is illustrated in FIG. 6. Computer 56may include a central processing unit (CPU) 80, a memory 82 and aninput/output (I/O) interface 84. The computer 56 is generally coupledthrough the I/O interface 84 to a display 86 for visualization andvarious input devices 88 that enable user interaction with the computer56 such as a keyboard, keypad, touchpad, touchscreen, mouse, speakers,buttons or any combination thereof. Support circuits may includecircuits such as cache, power supplies, clock circuits, and acommunications bus. The memory 82 may include random access memory(RAM), read only memory (ROM), disk drive, tape drive, etc., or acombination thereof. Embodiments of the present disclosure may beimplemented as a routine 90 that is stored in memory 82 and executed bythe CPU 80 to process the signal from a signal source 92. As such, thecomputer 56 is a general purpose computer system that becomes a specificpurpose computer system when executing the routine 90. The computer 56can communicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via a network adapter. One skilled in the art willrecognize that an implementation of an actual computer could containother components as well, and that FIG. 6 is a high level representationof some of the components of such a computer for illustrative purposes.

The computer 56 also includes an operating system and micro-instructioncode. The various processes and functions described herein may either bepart of the micro-instruction code or part of the application program(or a combination thereof) which is executed via the operating system.In addition, various other peripheral devices may be connected to thecomputer platform such as an additional data storage device and aprinting device. Examples of well-known computing systems, environments,and/or configurations that may be suitable for use with computer 56include, but are not limited to, personal computer systems, servercomputer systems, thin clients, thick clients, hand-held or laptopdevices, multiprocessor systems, microprocessor-based systems, set topboxes, programmable consumer electronics, network PCs, minicomputersystems, mainframe computer systems, and distributed cloud computingenvironments that include any of the above systems or devices, and thelike.

In some examples, the computer 56 is disposed within and considered apart of IR sensor 42 or display 86. In still other examples, thecomputer 56 may be co-located in both IR sensor 42 and display 86. Insome examples, full 2D images of a component such as a vane 66, that is,composite 2D images that include all 360 degrees or some other desiredportion of the external surfaces of the vane 66, are compiled from aplurality of individual images or exposures obtained by IR sensor 42 forsubsequent inspection by a qualified NDE inspector/operator. Inaddition, in some examples, the computer 56 is configured to combine aplurality of images of the vane 66 captured by IR sensor 42, and form acomposite image reflecting the image data of each of the plurality ofimages.

While particular embodiments of the present disclosure have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the disclosure. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this disclosure.

What is claimed is:
 1. A flash thermography device for generating aninfrared image of a turbine component located inside a turbine,comprising: a flash enclosure having an aperture; a flash source locatedin the aperture, wherein the flash source generates a light pulse thatheats the turbine component; an infrared sensor for detecting thermalenergy radiated by the turbine component wherein the radiated thermalenergy is transmitted through the aperture to the infrared sensor toenable generation of the infrared image; and an arm that holds the flashenclosure and infrared sensor inside the turbine.
 2. The deviceaccording to claim 1, wherein the flash source is a flash tube.
 3. Thedevice according to claim 1, wherein the flash source has an annularshape.
 4. The device according to claim 1, wherein the device is sizedto enable insertion of the device through an opening in the turbine. 5.The device according to claim 4, wherein the opening is through a pilotcone of a turbine combustor.
 6. The device according to claim 1, whereinthe arm is extendable and/or may be oriented as desired to enablepositioning of the infrared sensor in relative close proximity to aturbine component within the turbine to enable capturing of at least oneimage of the turbine component.
 7. The device according to claim 1,wherein the infrared sensor captures at least one image of at least onevane of the turbine.
 8. The device according to claim 1, wherein theturbine component includes a thermal barrier coating and/or a bondcoating.
 9. A flash thermography device for generating an infrared imageof a turbine component located inside a turbine, comprising: a flashenclosure having an aperture; a flash source located in the aperture,wherein the flash source generates a light pulse that heats the turbinecomponent; an infrared sensor for detecting thermal energy radiated bythe turbine component wherein the radiated thermal energy is transmittedthrough the aperture to the infrared sensor to enable generation of theinfrared image; and a moveable arm that holds the flash enclosure andinfrared sensor wherein the flash enclosure and infrared sensor areinserted through an opening in the turbine and movement of the armenables positioning of the infrared sensor and flash source in relativeclose proximity to a turbine component inside the turbine to enablecapturing of at least one image of the turbine component.
 10. The deviceaccording to claim 9, wherein the flash source is a flash tube.
 11. Thedevice according to claim 9, wherein the flash source has an annularshape.
 12. The device according to claim 9, wherein the opening isthrough a pilot cone of a turbine combustor.
 13. The device according toclaim 9, wherein the infrared sensor captures at least one image of atleast one vane of the turbine.
 14. The device according to claim 9,further including an optical camera and lamp attached to the enclosureto enable navigation of the device within the turbine.
 15. The deviceaccording to claim 9, wherein the component includes a thermal barriercoating and/or a bond coating.
 16. A method for inspecting a turbinecomponent located inside a turbine, comprising: providing a flashenclosure having an aperture; providing a flash source located in theaperture, wherein the flash source generates a light pulse that heatsthe turbine component; providing an infrared sensor for detectingthermal energy radiated by the turbine component wherein the radiatedthermal energy is transmitted through the aperture to the infraredsensor to enable generation of the infrared image; providing a moveablearm for holding the flash enclosure and infrared sensor; inserting theflash source and infrared sensor through an opening in the turbine andlocating the flash source and infrared sensor in relative closeproximity to a turbine component; capturing at least one image of theturbine component; and inspecting a turbine component characteristic.17. The method according to claim 16, wherein the opening is through apilot cone of the turbine combustor.
 18. The method according to claim16, wherein the infrared sensor captures at least one image of at leastone vane of the turbine.
 19. The method according to claim 16, whereinthe flash source is a flash tube.
 20. The method according to claim 16,wherein the flash source has an annular shape.